The present invention relates generally to hydrocarbonaceous compositions, such as asphalts and bitumens. More particularly the present invention generally relates to compositions for reducing the foul, undesirable or unpleasant odors emitted from such hydrocarbonaceous compositions.
Two primary uses of asphalt include road paving and roofing coatings. Asphalt-based roofing materials, such as roofing shingles, roll roofing, and built-up roofing, are installed on the roofs of buildings and residential dwellings to provide protection from the elements. When asphalt is used in roofing applications, the asphalt is first heated in a vessel, such as a gas-fired roofing kettle. As the temperature of the asphalt rises, volatile materials, such as hydrocarbons, sulfides, and mercaptans, are emitted that can have strong, unpleasant, foul odors. The odors emitted are not only unpleasant to smell, but they may also be an irritant to workers and/or other individuals in the vicinity of the vessel or to those who come within close range of the hot asphalt. For instance, the odorous fumes from the asphalt may cause headaches and/or irritation to the eyes and mucus membranes of the nose and throat, which can result in a deterioration of worker productivity and/or in increase in the number of sick days taken by workers.
Although the properties of asphalts used in paving generally differ from those used in roofing coatings, the problem of heating and release of volatile and malodorous compounds is common to both roofing and paving asphalts.
Many attempts to reduce undesirable odors emitted from odor-causing compounds are known in the art. Non-limiting examples of some of these approaches and odor-masking additives are set forth below.
In a first approach, exemplified by U.S. Pat. No. 6,488,988 to Trumbore, et al. and U.S. Pat. Nos. 5,989,662 and 6,107,373 to Janicki, et al. a physical barrier is formed on the surface of the asphalt to reduce fuming. Trumbore teaches that a substantially insoluble blanket material is added to the liquid asphalt to form a skin on the surface of the asphalt and reduce the fuming. Examples of blanket materials include polyurethane, polyethylene terephthalate, ground soda bottles, starch, and cellulosic materials. Janicki, et al. disclose methods of reducing fumes produced from a kettle of molten asphalt that includes adding about 0.25 to about 6.0% by weight of a polymer (e.g., polypropylene) to the asphalt. The polymer material preferably forms a skin across substantially the entire upper surface of the asphalt. Janicki teaches that at least a 25% reduction of the visual opacity of the fumes, at least a 20% reduction of the hydrocarbon emissions of the fumes, and at least a 15% reduction of suspended particulate emissions of the fumes is obtained.
In other approaches, essential oils are added as odor-masking compounds. For example, U.S. Pat. No. 5,271,767 to Light, Sr., et al. discloses a composition that consists essentially of (1) liquid asphalt, hot-mix asphalt, hot-mix, or cold lay asphalt with added latex and (2) an additive that contains a citrus terpene (4-isopropyl 1-methylcyclohexene) D-limonene mixed with a vegetable oil such as cottonseed oil, soya oil, rapeseed (canola) oil, peanut oil, etc. and a silicone oil dispersant. It is taught that when 0.5-1.0 parts of the composition are mixed with 99.0-99.5 parts liquid asphalt, the resulting liquid asphalt composition is substantially free of objectionable odors. Also, U.S. Pat. No. 7,037,955 to Timcik and U.S. Patent Publication No. 2006/0155003 to Timcik, et al. disclose methods for reducing odor in an oil based medium such as asphalt by adding an essential oil to the oil-based medium in an odor reducing amount. The essential oil may be one or more essential oils or essential oil components, and includes natural extracts of various products of aromatic plants and trees. Essential oils for use in the invention include ajowan, angelica root, angelica seed, aniseed china star, carrot seed, and fir needle, among many others. Examples of essential oil components include terpenes, alcohols, aldehydes, aromatics, phenolics, esters, terpene derivatives, non-terpene essential oil components, and terpene derivatives.
In yet another approach, U.S. Pat. Nos. 6,461,421 and 6,987,207 to Ronyak discloses compositions that include an odor-suppressing amount of an aldehyde or a ketone along with a carboxylic acid ester; and, in the latter case, also including a soy methyl ester. It is asserted that the composition significantly reduces the odor given off by a hydrocarbonaceous material such as asphalt.
Further, U.S. Patent Publication No. 2009/0314184 to Quinn, et al. discloses the use of certain aldehyde-containing compositions, with or without ketones but without esters, for reducing the malodors of asphalts. The disclosed aldehydes include 2-chlorobenzaldehyde, 4-chlorobenzaldehyde, alpha-methylcinnamaldehyde, 4-anisaldehyde, epsilon-cinnamaldehyde, vertraldehyde, 4-ethoxy-3-methoxybenzaldehyde, 3-ethoxy-4-hydroxybenzaldehyde, 3-nitrobenzaldehyde, vanillin, and cinnamaldehyde. In exemplary embodiments the composition consists solely of vanillin.
US patent Publication No. 2008/0146477 to Mentink, et al. discloses certain compositions and methods for treating asphalts and bitumens, the compositions containing certain specific esters of glutaric, succinic and adipic acids, or ethers or esters of a product derived from the internal dehydration of a sugar. The purpose of Mentinck's compositions appears to be a renewable source of additives to replace the current use of vegetable, mineral or fossil oils in the making of adjuvants for fluxes and binders for asphalts. The criteria set forth for these adjuvants do not mention odor-reduction.
US Patent publication 2009-0145330 to Draper, et al, discloses the use of certain inorganic zinc compounds like zinc oxide, zinc sulfonate or zinc carbonate, typically in nanoparticle formats, for reducing the evolution of hydrogen sulfide from asphalts.
U.S. Pat. No. 4,147,212 to Tisdale discloses the use of water soluble zinc ammonium carbonate salts for reduction of sulfides in drilling and working with oil and gas. US Patent Publication 2009/0012214 to Butler, et al. describes the use of heavy metal, water insoluble soaps (e.g. zinc stearate) to alter the viscosity and/or rheological properties of asphalts.
Thus there remains a need in the art for odor reduction using effective though low-cost compositions capable of reducing odors in hydrocarbonaceous materials such as asphalt.